1. Field of the Invention
This invention relates to a Gaussian-beam oscillator for microwave and millimeter wave which realizes microwave-millimeter wave oscillation with high spectral purity that can be directly extracted as beam output and, in addition, wave front synthesizes the outputs of a plurality of oscillator devices in a resonator to realize high-efficiency power combining.
2. Description of the Prior Art
For frequency-stabilization and phase noise reduction of a high-frequency oscillation output, the method of producing the oscillation coupled with a high-Q-value resonator is ordinarily used and, in particular, a planar circuit oscillator that ms a transistor circuit combined with a dielectric resonator (DRO) is widely used in the quasi-micro-microwave region. On the other hand, in the millimeter wave region, the conventional oscillators using a waveguide mount are still currently used, and since these ordinarily use a square or cylindrical resonator of the type with a partitioned waveguide, the Q value is low, so that a high-quality oscillation spectrum cannot be anticipated in combination with a millimeter wave transistor with a broad gain region. Attempts have been made to extend the use of the dielectric resonator employed in the microwave region into the millimeter wave region. However, the problem of decreasing resonator Q value with shorter wavelength is similarly present, and a need has arisen for new high-Q-value resonator technology suitable for combination with microwave and millimeter wave planar circuits, which are expected to spread and develop from now on.
In addition, in the millimeter wave and higher frequency range, since the output of an individual oscillator device is limited in principle, technology for power-combining the outputs of a plurality of oscillator devices is necessary for obtaining a large output, and in recent years experiments have been conducted using the Fabry-Perot resonator for this power combining. There has been reported a system in which, in the interior of a Fabry-Perot resonator having a set of facing plane-parallel mirrors or planar mirrors, a semiconductor device or a superconducting Josephson device was two-dimensionally disposed inside the resonator. It is considered, however, that problems exist in oscillator fabrication technology, including resonator technology, with the power combining efficiency obtained experimentally being low and the situation at present being one limited to basic experiments relating to power combining.
The idea of disposing an amplifying device inside a Fabry-Perot resonator can also be considered a method that analogously utilizes laser oscillation technology employing the light amplifying effect of induced discharge. With electric waves of a high frequency at or above microwaves, there are many cases in which it is convenient to treat them as beams similar to light, and, in particular, quasi-optical technology has an extremely important role to play in the millimeter wave region.
As a laser resonator using a combination of spherical mirrors, the Fabry-Perot resonator was intensively researched in the 1960s and has been established as an optical technology. In respect of electric waves of a frequency at or below near-millimeter waves (submillimeter waves in the several hundred GHz region), whose wavelengths are more than a number of three ciphers longer than light, however, this being a technology region on the border between optical technology and microwave technology, the sector of technology for connection and mutual transformation between the wave path technology from microwave technology and the beam technology from optical technology has many unsolved problems, while, moreover, microwave circuit technology, which has developed to a high level, is difficult to technically extend, as it is, for realization of a high-performance oscillator, so that a new technology for organically integrating optical beam technology and microwave and millimeter oscillator circuit technology has become important.
In the technologies mentioned in the foregoing, there are no concepts for realizing a microwave and millimeter wave oscillator which is appropriate for integral configuration with the modulation circuits, control circuits and other auxiliary circuits required in telecommunication and measurement technology and by connection with a high-Q-value resonator stabilizes frequency and reduces phase noise and which simultaneously enables the oscillation output to be extracted as a beam output With low sidelobe, and it is difficult to realize a compact and lightweight transmitter by combining these technologies. This adaptability to integral configuration with auxiliary circuits is, together with the microwave and millimeter wave monolithic integrated circuit (MMIC) technology now being actively developed, important for the realization of a compact, lightweight and practical transmitter. With the prior art power combining technology used in the case where it is necessary to amplify microwave and millimeter wave oscillation output, moreover, since the amplifying device is disposed inside the resonator, very major restrictions arise regarding connection with the modulation circuits, control circuits and various other auxiliary circuits which are a practical requirement for telecommunication, measurement and the like simultaneously with power combining, and because of these many problem points in application there is desired new microwave and millimeter wave oscillator configuration technology.
The present invention was accomplished in the light of the foregoing circumstances and resides in the provision of a new beam oscillator for microwave and millimeter wave with important characteristics as a practical technology, which utilizes a high-Q-value resonator technology applicable in the microwave and millimeter wave region, is able to stabilize oscillation frequency and reduce phase noise, oscillates directly in the linear polarization or circular polarization mode and enables the oscillation output to be extracted as a beam output with low sidelobe, and, further, is efficiently combinable with auxiliary circuits for various low speed.about.high speed modulation circuits and control that are indispensable for utilization with telecommunication technology and measurement technology, is suitable for integration with millimeter wave monolithic integrated circuits (MMIC) and the like, can enable realization of a quasi-planar transmitter, and can be augmented with high-efficiency power combining capability in cases where amplification of the oscillation output is necessary.